We are perfecting high resolution methods for the fractionation and display of restriction segments from complex genomes, primarily Drosophila. By this route we intend to identify restriction segments derived from: a) the Y chromosome and b) from a limited region near rosy (ry ion) that is present in multiple duplications. As a companion study, we are injecting DNA into embryos to confirm and develop a functional bioassay from DNA segments. This work is proceeding with the collaboration of Howard Schneiderman at Irvine. Finally, clonal libraries of various sorts, Drosophila, mouse and Neurospora, are being made or are in the planning stages.